Martin Rozenfeld

Clinical electron-beam dosimetry: report of AAPM Radiation Therapy Committee Task Group No. 25.

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Cylindrical chamber dimensions and the corresponding values of Awall and Ngas/(NxAion).

Cylindrical ionization chamber descriptions and physical dimensions that are necessary for the calculation of Awall and Ngas are presented. Also included are the corresponding calculated values of Awall and Ngas/(NxAion).

Application of fission track detectors to californium-252 neutron dosimetry in tissue near the radiation source

Fission track detectors were applied to a unique problem in neutron dosimetry. Measurements of neutron doses were required at locations within a tumor of 1 cm diameter implanted on the back of a mouse and surrounded by a square array of four 252Cf medical sources. Measurements made in a tissue-equivalent mouse phantom showed that the neutron dose rate to the center of the tumor was 2.18 rads micrograms-1 h-1 +/- 8.4%. The spatial variation of neutron dose to the tumor ranged from 1.88 to 2.55 rads micrograms-1 h-1. These measurements agree with calculated values of neutron dose to those locations in the phantom. Fission track detectors have been found to be a reliable tool for neutron dosimetry for geometries in which one wishes to know neutron dose values which may vary considerably over distances of 1 cm or less.

On the application of a liquid-dielectric ionization chamber to 252 Cf dosimetry.

Our investigations of an iso-octane-filled liquid-dielectric ionization chamber indicate that this dosimeter is well suited for the measurement of dose distributions at distances close to 252Cf interstitial implant sources. Initial research has shown that such an instrument provides good discrimination between the radiation components of a mixed field and possesses excellent sensitivity. Calculations indicate that iso-octane will yield a neutron and gamma-ray dose response independent of energy over a major part of the 252Cf spectral range, while transmission measurements have demonstrated that the liquid causes little perturbation of the radiation field.

An assessment of RBE of Californium-252 for C57-Black/6 mouse fibrosarcoma by a precise afterloading technique.

Afterloading techniques were developed for the in vivo assessment of the RBE of californium-252 with respect of radium-226 using a fibrosarcoma in mice. The afterloading holder positions sources so that the tumor is uniformly irradiated. Using the end points of tumor volumetric studies up to 150 days after irradiation, it was found that the RBE ranged from 5-8 at clinically relevant dose rates and total doses.

CORADS (Computerized Oncology Radiation and Data System)

The CORADS project is an answer to the need for more accurate and complete data concerning treatment of radiation therapy patients. Compendiums of information are needed for research, but obtaining them from traditional medical records is an increasing problem. The overall goal of the CORADS project is to collect data in an innovative fashion and to provide them in a reorganized and integrated format when requested.